Toyota Repair: 93 Camry V6 overheating, head gasket leak, radiator hoses

Question
I have a 93 Camry with a v6.  I had a new Toyota engine put in it 63,000 miles ago.  The overheating problem just started a week or so ago.  It can drive it 30-40 miles on the freeway and the temperature gauge will start to climb after i get off the freeway and drive a few more miles.  The temp gauge will climb to over half way (1/4 of the way seems to be normal for it)and maybe a little further and then drop down a little and then back up to near the red line.  After i pull off to check it out then i notice that the water is boiling into the reservoir and spuing out over the engine.  It almost got hot enough this last time that it tried to melt the reservoir canister.  The first time it overheated i filled it with coolant and change the radiator cap which seem to take care of the problem for two days.  After about two days it overheated again on my son.  After a couple of hours i got in it and drove it home about 50 miles away.  It again overheated a couple of more days after that.  The return and supply radiator hoses are both getting hot so i ruled out the thermostat.  I suspected a head gasket, but there is absolutely no smoke, no coolant in the oil, and no air bubbles coming from the radiator when i punch on the accelerator a few times.  The fan seems to be hydraulically controlled and comes on immediately after you start the engine at a slow speed and steps up the speed when i turn on the AC, but i have never seen the fan step when i have let it idle for 30-40 minutes quite like it does when the AC is turned on.  Should i see a noticeable difference in the fan speed after about 20-30 minutes of idling?  Could i have a head gasket leak?  I am lost on this mysterious overheating problem.  Thanks for you help in advance.

Thanks, Michael

Answer
This hydraulic fan system is controlled by pressure from the power steering pump, on top of the pump is a pressure regulating solenoid that's controlled by a seperated electronic contro unit, in most cases I have seen like this the electrical connector on top of the pump is not connected so check there first to see if the connector is on.